Electric circuit interrupter



Feb. 14, 1939. o. c. PRINCE ET AL ELECTRIC CIRCUIT INTERRUPTER FiledNov. 11, 1937 e 9 ..c% m Smim MP FPt O mmw ,mwm D m Patented Feb. 14,1939 PATENT OFFICE ELECTRIC cracm'r INTERRUP'I'ER David 0. Prince,Swarthmore, and Percy Bartlett, Springfield, Pa., assignors to GeneralElectric Company, a corporation of New York Application November 11,1937, Serial No. 174,066

8 Claims.

Our invention relates to electric circuit interruptersfor high voltagepower circuits, more particularly to circuit breakers of the impulsetype wherein a piston or the equivalent thereof is utilized to projectarc-extinguishing liquid through the arc to be interrupted.

Power breakers of the above type have been proposed wherein the arcpressure tending to oppose or block normal operation of the piston iscompensated to a certain degree by admitting arc pressure to theopposite side of the piston. While improving the breaker operation,certain diihculties including uncertain interruption at low currentvalues when the arc pressure is very low and improper utilization of thearc pressure are still present.

A principal object of our invention is the provision of an improvedcircuit breaker oi the. im-

pulsetype that is simple and compact in design, and eflicient, rapid andpositive in its interrupting operation throughout the entire range ofcurrent rating.

Our invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize our invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

Referring to the drawing the 1 single figure thereof is an elevationalview, partly in section,

of an electric circuit breaker embodying our invention.

The circuit interrupter illustrated by way of example comprises a mainhousing or casing l adapted to contain a suitable arc-extinguishingliquid such as oil. Immersed in the arc-extinguishing liquid is an arcinterrupting device generally indicated at 2 supported at the lower wallof the housing by an insulator 3. The arc-extinguishing device includesa conducting or fixed contact structure 4 supported in part by a secondinsulator 5 serving as the lead-in terminal conductor bushing betweenthe fixed contact structure 4 and the exterior circuit. The otherterminal of the breaker includes a contact 6 suitably mountedwithrespect to an insulator i that i also serves as a lead-in terminalconductor bushing in the wall of the housing I.

The movable contact structure associated with the arc-interruptingdevice 2 comprises a contact rod 8 adapted to make sliding contact with.the contact 6 and suitablyguided for reciprocal rectilinear movement.The means for effecting movement of the rod contact 8 comprises alinkage mounted within a spherical extension 9 of the main housing, theextension being attached to the housing through an intermediatecylindrical member l0.

The interrupting device 2 including the fixed contact structure 4 isprovided with a cylindrical portion H open at its opposite ends. Apiston I2 is mounted for reciprocal movement within the cylinder and isattached through an insulating rod l3 to the linkage above referred toin the spherical extension 9. The upper end of the arcinterruptingdevice 2 is closed by a pair of spaced insulating plates I4 and I5through which the contact rod 8 is moved in alined apertures 16 toengage the relatively fixed contact structure. The spacing between theplates l4 and I5 forms 7 a lateral passage ii that communicates at onerod 8, there is provided an intermediate floating contact l9 disposedbetween the fixed contact structure 4 and the rod contact 8 arranged sothat two arcs are formed in series when the complete contact structureis separated. The intermediate contact i9 is mounted in and supported byan insulating partition 20 forming with the conducting structure 4pressure chambers 2| and 2| in communication with the lower and upperfaces respectively of the piston l2. A vent 20" of suitable bore andlocation in the partition 20 permits the piston [2 to descend during theclosing or resetting stroke. During this movement the chamber 2| isscavenged of residual gases resulting from the preceding arcinterruption.

The contact separation within the chamber 2| takes place between thearcing tips 4' of the fixed contact and IQ of the intermediate contact.A spring 22 seated at the opposite side of the partition 20 tends tobias the intermediate contact away from engagement with the contact tip4'. The intermediate contact is also provided with arcing tip IQ" forcoacting with the rod contact 8 which is illustrated in alinementtherewith through the apertures I5. Accordingly, it will be noted thatwhen the rod contact 8 is lowered to close the circuit between theterminals 5 and I, the intermediate contact will The circuit is thencomscribed, the contact tips d and it first separating due to thefollowing movement of the intervelocity transversely of the arcwithinthe pasmediate contact I9 under the influence of spring 22. When theintermediate contact reaches its upper limit of travel, as illustrated,separation of the rod contact-3 and contact tip it" takes placeresulting in a second break in the circuit. This second break is in thetransverse passage ill through which oil is driven by the piston i2 in amanner presently to be described for interrupting the arc.

The operating linkage previously referred to in the housing extension 9is arranged to cause simultaneously both opening movement of the rodcontact 8 and an upward wormng stroke of the piston I2. By way ofexplanation the draw-' ing illustrates the mechanism in the process ofbeing closed, piston l2 being first depressed and, the rod contact 8then lowered to engage the contact structure within the arc-interruptingde-' vice.

When the breaker is opened, pressure generated by the are formed betweenthe contact tips 4' and [9' in the pressure chamber 2i acts on the lowerside of the piston l2 tending to assist the upwardly pulled piston indriving 'a stream of oil through the passage l1 transversely of the aresubsequently formed at the contact 8. In the case of arc currents ofappreciable magnitude, this operation'is very effective and the pistonpropelled by both mechanical and arc-gem, erated pressures drives ablast of oil at high sage il.

During the interruption of low currents, however, the generated arcpressure maybe ,of quite a low value or slow in forming. Henceau-retardation of the piston would ensue because of i s tendency toproduce a vacuum or negative pressure on its under side di'iring itsupward travel.

' This would lessen the zintensity nf an early and decisive oil blastthrough the passage it. For the purpose of eliminating-this hazard anonreturn valve -23 is provided for the chamber 25 arranged so that oilis drawn into the chamber from the main housing i when the piston ittends to create a vacuum in the chamber due to insufiicient arcpressure. The valve 23 obviously remains closed when the arc pressure issufiicient to aid the piston i2. That is, the pressure chamher it isprovided with valve means arranged to close the chamber when the arcpressure therein has or exceeds a predetermined value, and also ar=ranged to open the chamber when said pressure is less than saidpredetermined value.

Accordingly, the piston is efiectiv'e throughout the entire range ofcurrent rating to project an effective oil blast through the main arewithin the passage ii. In the caseof heavy current arcs, it will benoted that the piston E2, in mov-- ing to the dotted line positionshown, establishes a wide communication between chambers Zi2i' to form acommon pressure region. He-

terrupting device.

ber within which one of said break areas-er pendently to thebest-advantage as current conditions may dictate.

The operating linkage for the contact rod d and the piston 12 abovereferred to may comprise any suitable arrangement for effecting quickseparation of the contacts and a positive stroke of the piston. In thepresent instance, there is shown a main operating shaft 241 transverselypivotally connected to a link 30 near the midportion thereof, the link30 also being pivotally connected at 38 to the upper end of the contactrod 8.

The lever 27 is also pivotally connected to a floating lever 32 that isin turn loosely connected to the insulating rod I3 of the pistbn 52. Apin 33 at one end of the link 30 operates in a slot 32' in the floatin'glever 32, the movement of the opposite end of the floating lever beingcontrolled in one direction by an abutment 36. v

The linkage is shown in a partially closed position in which theoperating shaft 2% has been rotated counter-clockwise towards thecircuit closing position so as to extend or charge the spring 35. Thespring in this position biases thepiston l2 through the insulating rodis in an upward or blast-producing direction. Further clockwise rotationof the shaft 25 will cause the lever 2'8 to rotate the'link 28 also in acounterclockwise direction thereby rotating the link 36 clockwise andmoving the contact rod 8 downward into contact engagement within thearc-in- This operation also will extend the biasing spring 36 tending tomove the contact rod 8 in a circuit-opening direction.

rotated to a point so that the crank arm 25 and link 26 are slightlyoverset so as to hold the breaker in the circuit-closing position. Inthe circuit-opening operation the shaft 2% is rotated in a clockwisedirection so that the linkage will N be released and the springs 35 and36 are effective to cause simultaneous movement or the con tact rod 8and piston i2 upward, thereby causing separation of the breaker contactsand extin guishing of the arc.

It should be understood that our invention is not Limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing iron; the spirit of our invention.

What we claim as new'and desire to secure by Letters Patent of theUnited States; is:

1. ,An electric circuit breaker of the impulse type comprising anarc-extinguishing liquid, relatively movable contact structure adaptedto form two breaks in series in said liquid upon opening of the circuit,means defining a pr ssure chamis formed,

. tween said chamber and said passage arranged a piston communicatingwith said chamber and arranged to project arc-extinguishing liquidthrough the are at said other break, means for actuating said pistonindependently of said are pressure, and means for compensating low arcpressure in said chamber when said piston tends to create a negativepressure therein.

2. An electric circuit breaker oi the impulse type comprising anarc-extinguishing liquid, relatively movable contact structure adaptedto form two breaks in series in said liquid upon opening of the circuit,means defining a pressure chamber within which one of said breaks isformed and a transverse passage within which the other of said breaks isformed, a piston interposed beso that arc pressure in said chamber tendsto move said piston in a direction to cause a blast *ber and arranged toproject arc-extinguishing oi arc-extinguishing liquid through saidpassage for interrupting the are at said other, break, means foractuating said piston independently of said are pressure, and a valveassociated with said chamber for compensating low arc pressure thereinwhensaid piston tends to' create a negative pressure'in said chamber.

3'. An electric circuit breaker of the impulse type comprising anarc-extinguishing liquid, relatively movable contact structure includinga fixed contact, an intermediate contact and a main movable contactadapted to form two breaks in series in said liquid upon opening of thecircuit, means defining a pressure chamber within which thebreak betweensaid fixed and intermediate contacts is formed, said intermediatecontact coacting with said main movable contact exteriorly of saidchamber, a piston communicating with said chamliquid through the arc atthe break between said intermediate and main movable contacts, the

arc pressure in said chambertending to aid said projection ofarc-extinguishing liquid through said other are, means for actuatingsaid piston independently of said are pressure, and valve meanscontrolling a port in said chamber arranged to close said chamber in thecase of heavy current interruptions whereby said piston is assisted bythe resulting arc pressure.

4. An electric circuit breaker of the impulse type comprising anarc-extinguishing liquid, an arc-interrupting device immersed. in saidliquid having a pressure chamber and a transverse exhaust passage, afixed contact disposed in said chamber, a floating contact coactingtherewith and extending through a wall of said-chamber, a movablecontact coactingwith said floating contact exteriorly of said chamber insaid exhaust passage, a piston interposed between said chamber andpassage arranged so that are pressure. formed in said chamber betweensaid fixed and floating contacts tends to drive arc-extinguishing liquidthrough said passage and transversely of the are between said floatingand movable contacts, means for actuating said piston independently ofsaid are pressure, and means associated with said chamber forcompensating low arc pressure in said chamber when said piston tends tocreate negative pressure therein.

5 An electric circuit breaker or theimpulse type comprising anarc-extinguishing liquid, relativeiy movable contact structure includinga fixed a the break between said fixed and intermediate contacts isformed, a non-return valve associated with said pressure chamber, saidintermediate contact coacting with said main movable contact exteriorlyof said chamber, a piston communicating with said chamber and arrangedtoproject arc-extinguishing liquid through the are at the break betweensaid intermediate and main movable contacts, the arc pressure in saidchamber tending to aid said projection of arc-extinguishing liquidthrough said other are, and means for actuating said pistonindependently of said arc pressure.

6. An electric circuit breaker oi the impulse type comprising anarc-extinguishing liquid, relatively movable contact structure adaptedto form two breaks in series upon opening of the circuit, means defininga pressure chamber within which one of said breaks is formed in saidliquid, a piston communicating with said chamber and arranged toprojectarc-extinguishing liquid through the arc at said other break, means foractuating said piston independently of the arc pressure in said chamber,and means for openingsaid chamber to said liquid and adapted to form twobreaks in series upon opening of the circuit, means defining a pressurechamber within which one of said breaks is formed, means forming aninterrupting chamber within which the other of said breaks is formed, apiston communicating with both chambers and arranged to projectarc-extinguishing liquid through the arc in said interrupting chamber,the arc pressure in said pressure chamber tending to aid said projectionof arc-extinguishing liquid, means ior actuating said pistonindependently of said are pressure, and valve means coactmg with saidpressure chamber arranged to be closed when said are pressure has orexceeds a predetermined value, and arranged to be opened when said arepressure is less than said predetermined value.

8. An electric circuit breaker oi the impulse "type comprising'anarc-extinguishing liquid, relatively movable contact structure adaptedto term two breaks in series upon opening of the circuit, means defininga pressure chamber within which one oi said breaks is formed in saidliquid, at piston communicating with said chamber and arranged toproject arc-extinguishing liquid through the are at said other break,actuating means for eflecting a working stroke of said piston, and valvemeans controlling a port in said chamber communicating with a regionebrt'eriorly thereof, i

mm c. memos.

